The present invention relates, in general, to a semiconductor device and, more particularly, to a method of manufacturing a semiconductor device, which can improve the yield and quality of the semiconductor device of 60 nm or less.
Semiconductor memory devices for storing data can be classified into volatile memory devices or nonvolatile memory devices. A volatile memory device loses data when a power supply is removed, whereas a nonvolatile memory device retains data when a power supply is removed.
A nonvolatile memory device includes a flash memory device. A unit cell of the flash memory device generally includes an active region defined on a specific region of a semiconductor substrate, a tunnel insulating layer formed on the active region, a floating gate formed on the tunnel insulating layer, a gate interlayer insulating layer formed on the floating gate, and a control gate electrode formed on the gate interlayer insulating layer. In particular, a flash memory device has been widely used with MP3 players, digital cameras, memory for bios storage of a computer, mobile phones, portable data storage devices and the like.
The flash memory cell can store data as external voltage applied to the control gate electrode is coupled to the floating gate. Accordingly, to store data within a short period of time and at a low programming voltage, the ratio of voltage applied to the control gate electrode to voltage applied to the floating gate must be high. The ratio of voltage applied to the control gate electrode to voltage applied to the floating gate is called a “coupling ratio”. The coupling ratio can be expressed by the ratio of the capacitance of the gate interlayer insulating layer to the sum of the capacitance of the tunnel insulating layer and the gate interlayer insulating layer.
As devices become high integrated, a gate etch process in devices 60 nm or less becomes difficult.